[DNM] Fix top level script mode vars #86111
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Previously we would allow these in Sema and diagnose them in SILGen, but allowing them in Sema is unsound because it means the constraint system ends up kicking interface type requests for declarations that should be type-checked as part of the closure itself. Adjust the name lookup logic to look through parent closures when detecting invalid forward references. For now we don't fallback to an outer result on encountering a use-before-declaration to preserve the current behavior. I'm planning on changing that in the next commit though. rdar://74430478
If we encounter a variable declared after its use within a closure, we can fallback to using an outer result if present. This matches the behavior outside of a closure and generally seems more consistent with the behavior we have if we also find an inner result. rdar://163656720
This allows the query to be consistent both during type-checking and after.
Bindings in closures must be type-checked together with the surrounding closure, add an assertion to make sure we don't try this. Carve out an exception for code completion and error cases which may still kick lazy type-checking. We ought to eventually fix up all the error cases cases though since they imply we're leaving bits of the AST un-type-checked.
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@swift-ci please test source compatibility |
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Enforce that a PatternBindingDecl always shares the same DeclContext as any VarDecls it binds. Then change top level vars in script mode such that they are treated as local vars unless you add an access control keyword. The implementation is pretty hacked together and a lot more test cases need updating, but interested to see what the source compatibility impact is.